1. Field of the Invention
The present invention relates to a winding method and a winding apparatus for producing stators for electric motors, wherein a plurality of stator cores divided to have a toothshaped configuration are assembled into an annular structure, and the stator cores are subjected to winding to form a stator.
2. Description of the Related Art
A conventional stator for an electric motor has a structure comprising a plurality of radially directed projections which are formed on an inner circumferential surface of a substantially cylindrical body, including a lead wire which is wound onto grooves of the projections. Therefore, the conventional stator has had an inconvenience that the operation for winding the lead wire is extremely complicated.
In view of such an inconvenience, a method for producing a stator is known, as disclosed in Japanese Laid-Open Patent Publication No. 7-163070, in which a plurality of divided stator cores are prepared. A lead wire is wound onto each of the stator cores, and then the stator cores are fitted to one another to form an annular configuration so that the stator is produced.
In general, those adopted for producing the stator include the centralized winding coil system in which the lead wire is wound onto each of the stator cores as described above, as well as the lap winding coil system in which the lead wire is wound onto the stator cores while spanning a plurality of stator cores. However, in the case of such a lap winding coil system, it is difficult to apply the foregoing conventional technique thereto.
For this reason, an operation is generally adopted, in which an open stator is integrally formed to apply a lap winding coil thereto. However, the material is consumed at a poor yield in the press punching step for integrally forming the open stator. As a result, a problem is pointed out in that this process is extremely uneconomical. Further, the operation for winding the lead wire is complicated, and a problem arises in that the productivity is low.
Additionally, in the case of a commutator motor, it is necessary that a commutator member (commutator) is subjected to winding. Therefore, the operation for winding the lead wire is considerably complicated, and a problem arises in that the productivity is extremely low.
On the other hand, an insulator (insulating material) is usually allowed to intervene between a stator core and a coil in order to prevent the both from electric connection. Therefore, the operation for winding the lead wire while allowing the insulator to intervene therebetween is considerably complicated. As a result, a problem arises in that the productivity is extremely low.